Question 1170856
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A rectangle having the greatest area with the given perimeter is a square.


See the lesson

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/A-rectangle-with-the-given-perimeter-which-has-the-maximal-area-is-a-square.lesson>A rectangle with a given perimeter which has the maximal area is a square</A>

in this site, &nbsp;where this fact is proved with all needed details and explanations.


Therefore, &nbsp;under given condition, &nbsp;the greatest area is provided by a &nbsp;SQUARE 

with the side length of &nbsp;&nbsp;20 = 80/4 meters.


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Solved, &nbsp;answered and explained.  &nbsp;&nbsp;//&nbsp;&nbsp;And completed.